Ground peg, and device and method for the production thereof

Abstract

The invention relates to a ground peg ( 10 ) which is made from a steel tube ( 11 ) and comprises an upper cylindrical section ( 12 ), a lower section ( 16 ) that tapers towards the bottom to form a tip ( 14 ), and an external thread ( 26 ) that extends along at least part of the lower section ( 16 ) and is formed from a continuous sheet metal strip ( 28 ) welded onto an external surface ( 32 ) of the ground peg ( 10 ) by means of a continuous or regularly interrupted fillet weld ( 34 ). The external thread ( 26 ) has a nearly constant pitch (S) and slope (a) relative to a longitudinal axis ( 40 ) of the ground peg ( 10 ) along the entire length of the external thread ( 26 ). The invention further relates to a method or producing such a ground peg ( 10 ). In said method, the external thread ( 26 ) is laterally fed to the external surface ( 32 ) of the rotating steel tube as an elongate sheet metal strip ( 28 ) and is welded onto said external surface ( 32 ), the steel tube ( 11 ) being moved relative to the feeding point of the sheet metal strip ( 28 ) at a regular advance (V) in the longitudinal direction of the steel tube ( 11 ). The invention finally relates to a device for producing such a ground peg ( 10 ). Said device comprises a mechanism for clamping and rotating the steel tube as well as a mechanism ( 44 ) for feeding the sheet metal strip ( 28 ) to the external surface ( 32 ) of the steel tube ( 11 ) such that the sheet metal strip ( 28 ) tangentially rests there against.

1. A method for producing a ground peg made from a steel tube and comprising at least an upper cylindrical section, a lower section tapering towards a bottom to form a tip, and an external thread extending along at least a part of the lower section, the external thread being formed from a continuous sheet metal strip welded onto an external surface of the ground peg using a continuous or regularly interrupted fillet weld, the method comprising:
 laterally feeding the external thread to the external surface of the steel tube as the steel tube rotates, the external thread being an elongate sheet metal strip; and 
 welding the sheet metal strip onto said external surface; and 
 moving the steel tube relative to a feeding point of the sheet metal strip at a regular advance in a longitudinal direction of the steel tube; 
 wherein the upper section and the lower section of the ground peg is a single piece of a continuous steel tube section, wherein at least three longitudinal slots are inserted in the lower section by removing triangle-shaped sections in the area of the longitudinal slots, wherein the at least three stripe portions formed thereof peak in each case in a cusp, and wherein the at least three stripe portions of the ground peg are joined together by applying and welding of the sheet metal strip of the external thread and pressed together to form the tip. 
 
     
     
       2. The method as recited in  claim 1  wherein the sheet metal strip of the external thread is fed and welded along its entire length with a nearly constant pitch and slope relative to a longitudinal axis of the ground peg. 
     
     
       3. The method as recited in  claim 1  wherein the sheet metal strip of the external thread is fed in a nearly constant angle to a longitudinal axis of the steel tube, wherein this feeding angle is the slope of the external thread. 
     
     
       4. The method as recited in  claim 1  wherein the sheet metal strip of the external thread is fed and welded with longitudinal sides nearly perpendicular to a longitudinal axis of the steel tube. 
     
     
       5. The method as recited in  claim 1  wherein the steel tube of the ground peg rotates during the welding of the sheet metal strip in an area of the upper cylindrical section with an increased rotation speed compared to the regular advance of the steel tube with reference to the feeding point of the sheet metal strip. 
     
     
       6. The method as recited in  claim 1  wherein the steel tube of the ground peg rotates during the welding of the sheet metal strip in an area of the lower section with an increased rotation speed compared to the regular advance of the steel tube with reference to the feeding point of the sheet metal strip. 
     
     
       7. The method as recited in  claim 6  wherein the rotation speed of the steel tube is constantly increased with diminishing spacing of the sheet metal strip at an external surface of the steel tube to the longitudinal axis of the steel tube. 
     
     
       8. The method as recited in  claim 5  wherein the steel tube rotates quicker the smaller a spacing of the sheet metal strip at an external surface of the steel tube to the longitudinal axis of the steel tube is. 
     
     
       9. The method as recited in  claim 1  wherein the sheet metal strip is pressed with a defined preload force in the area of the weld in a perpendicular direction against the external surface of the steel tube. 
     
     
       10. The method as recited in  claim 9  wherein a spacing of the weld to the longitudinal axis of the steel tube is measured and the relation between the rotation speed of the steel tube and the regular advance of the steel tube is adjusted depending on the detected spacing compared to the weld of the sheet metal strip with the external surface of the steel tube. 
     
     
       11. The method as recited in  claim 10  wherein the rotation speed of the steel tube is increased with a constant remaining regular advance during the feeding and welding of the sheet metal strip in the area of and in direction to the lower section. 
     
     
       12. The method as recited in  claim 10  wherein the regular advance between the steel tube and the sheet metal strip is reduced with a constant remaining rotation speed of the steel tube during the feeding and welding of the sheet metal strip in the area of and in direction to the lower section. 
     
     
       13. The method as recited in  claim 1  wherein the weld is a tack weld.